Refractive index tools and method. A refractive index tool includes a wave source configured to generate a wave; a transparent rod configured to receive the wave from the wave source; and a wave detector configured to receive the wave from the transparent rod. The wave source is provided at a first end of the transparent rod and the wave detector is provided at the first end or a second end of the transparent rod so that the wave emitted by the wave source travels through the transparent rod and experiences total internal refraction prior to arriving at the wave detector.